1. Field of the Invention
The present invention relates to a split type oil hydraulic piston pump and a pressurized oil feed circuit for feeding pressurized oil to two hydraulic actuators by making use of a split type oil hydraulic piston pump.
2. Description of the Prior Art
Heretofore, generally classifying the oil hydraulic piston pumps, axial type oil hydraulic piston pumps and radial type oil hydraulic pumps have been known, and as oil hydraulic piston pumps adapted for high-speed, high-pressure and variable-capacity operations the axial type oil hydraulic piston pumps have been commonly used. In these axial type oil hydraulic piston pumps is included a swash plate type piston pump which is also known as a KV pump. Among these swash plate type piston pumps, a piston pump constructed in such manner that a single pressurized oil suction slot and a plurality of pressurized oil delivery slots are formed in one valve plate that is slidably making contact with a single cylinder block provided with a plurality of pistons and pressured oil may be fed from these delivery slots to a plurality of hydraulic actuators, is known as a split type oil hydraulic pump.
A difficulty associated with such a split type oil hydraulic pump in the prior art was generation of a large variation of a flow rate when the pistons deliver the pressurized oil to the respective delivery slots. In addition, when each piston passes through the valve plate portion between the plurality of delivery slots, the delivered oil is interrupted by the valve plate, resulting in generation of a large trapping pressure, and hence the oil delivered from the piston cannot be effectively and perfectly utilized. Furthermore, in the case where the pressurized oil is fed from the plurality of pressurized oil delivery slots to a plurality of hydraulic actuators, it is necessary to feed a larger amount of pressurized oil to a hydraulic actuator that is more heavily loaded. Moreover, the larger a load of a hydraulic actuator is, the more is generated oil leakage.